He falsifies them to suit his own selfish interests...
He falsifies them to suit his own selfish interests, or in the interests of other groups as the case may be, and thus he does not define legality in its scientific and objective forms. There are numerous examples proving this human frailty. For instance when man discovered the harms of alcoholic drinks, adultery, usury trade monopolies and the like, he prohibited none of them in utter disregard to the proven scientific facts.
On the contrary, he resorted to sophisticated means to conceal the actual truth. Therefore, leaving the task of judgment and legislation to Allah alone is the only way of saving man from doom beau. Allah the Creator is the only One Who knows all the hidden secrets of mankind and life: “أَلَا يَعْلَمُ مَنْ خَلَقَ وَهُوَ اللَّطِيفُ الْخَبِيرُ “ [67:14] Does He not know, Who created? And He is the Knower of the subtleties, the Aware.
Allah alone is able to communicate what He wants to by means of the best possible way understandable to mankind. The way of the prophets and the divine revelation to them, disclosed in explicit verbal forms that are clear in meaning and implication.
This was actually what had been preached throughout the course of history by all the Divine Laws and Messages: “وَمَا أَرْسَلْنَا مِنْ رَسُولٍ إِلَّا بِلِسَانِ قَوْمِهِ لِيُبَيِّنَ لَهُمْ ۖ فَيُضِلُّ اللَّهُ مَنْ يَشَاءُ وَيَهْدِي مَنْ يَشَاءُ ۚ وَهُوَ الْعَزِيزُ الْحَكِيمُ “ [14:4] And We did not send any messenger but with the language of his people, so that he might explain to them clearly; then Allah makes whom He pleases err and He guides whom He pleases and He is the Mighty, the Wise.
(This is) a Book which We have revealed to you that you may bring forth men, by their Lord's permission from utter darkness into light-- to the way of the Mighty, the Praised One, “إِنَّ هَٰذَا الْقُرْآنَ يَهْدِي لِلَّتِي هِيَ أَقْوَمُ وَيُبَشِّرُ الْمُؤْمِنِينَ الَّذِينَ يَعْمَلُونَ الصَّالِحَاتِ أَنَّ لَهُمْ أَجْرًا كَبِيرًا “ [17:9] Surely this Quran guides to that which is most upright and gives good news to the believers who do good that they shall have a great reward.
Imam Ja’far Al-Sadiq (AS) drawing our attention to these facts has rightly remarked: "The Qur'an is a covenant of Allah to His creatures.